This invention relates to a method and system for making a curved laminated vehicle windshield, using an ion beam source(s) to deposit at least one diamond-like carbon (DLC) inclusive coating on a curved exterior surface thereof.
Laminated curved vehicle windshields are known in the art. Such windshields typically include first and second curved glass sheets/substrates separated from one another by an interlayer of a material such as polyvinyl butyral (PVB). Unfortunately, conventional windshields typically are not hydrophobic in nature, and thus do not easily repel or shed rain water. Moreover, conventional windshields are often not as scratch resistant as would otherwise be desired.
Hydrophobic coatings are known in the art. However, a problem arises as to forming same on a windshield because the PVB layer of the windshield, once in place between the sheets to bond them together, cannot withstand high temperatures or else delamination may occur. Moreover, known hydrophobic coatings typically are not mechanically durable enough (e.g., scratch resistant) to withstand the punishing environments in which vehicle windshields are utilized (e.g., high speed, heat, sun, snow, rain, etc.).
It has heretofore not been appreciated by those skilled in the art how to efficiently deposit a hard/durable coating onto the exterior surface of a curved vehicle windshield.
An object of this invention is to provide a hard/durable coating on the exterior surface (or convex surface) of a laminated curved vehicle windshield or other curved substrate.
Another object of this invention is to provide a method of forming a hydrophobic hard/durable coating on the exterior surface of a vehicle windshield using a low temperature process so that an interlayer(s) located between the two glass sheets of the windshield is/are not damaged during the process of forming the coating. The coating comprises diamond-like carbon (DLC) in preferred embodiments.
Coatings herein my be hydrophobic or non-hydrophobic in different embodiments. When hydrophobic, the nature of such DLC-coated windshields may be characterized by relatively high initial contact angles xcex8. For example, coated windshields herein may be characterized by an initial contact angle xcex8 (i.e. prior to being exposed to environmental tests, rubbing tests, acid tests, UV tests, or the like) of at least about 55 degrees, more preferably of at least about 80 degrees, even more preferably of at least about 100 degrees and most preferably of at least about 110 degrees.
Another object of this invention is to fulfill one or more of the above-listed objects.
In certain exemplary embodiments, this invention fulfills one or more of the above listed needs or objects by providing a method of making a curved laminated vehicle windshield, the method comprising:
providing first and second glass sheets;
placing the first and second glass sheets in juxtaposed relation with one another and heat bending the sheets together;
positioning an interlayer between the two heat bent glass sheets;
heating the glass sheets with interlayer therebetween in order to laminate the first and second glass sheets to one another via at least the interlayer, thereby forming a curved laminate including a convex surface and a concave surface;
ion beam milling the convex surface of the curved laminate in order to shave off or remove a portion of the first glass sheet thereby forming a milled convex surface of the curved laminate; and
ion beam depositing a diamond-like carbon (DLC) inclusive coating on the milled convex surface of the curved laminate using a non-focused ion beam, thereby forming a vehicle windshield having an outer or convex surface including a DLC inclusive coating thereon.
Certain other embodiments of this invention fulfill one or more of the above-listed objects by providing a method of making a curved coated article, the method comprising:
providing a glass sheet;
heat bending the glass sheet to form a bent glass sheet having a convex surface and a concave surface; and
ion beam depositing a diamond-like carbon (DLC) inclusive coating on the convex surface of the bent glass sheet.
This invention will now be described with respect to certain embodiments thereof, along with reference to the accompanying illustrations.